1. Field of the Invention
The invention relates to stator of a rotary electric machine, that includes a stator core in which a plurality of teeth that protrude toward a rotor are arranged spaced apart from each other, and in which a slot is formed between the teeth, and a coil that passes through the slot and is wound around the teeth.
2. Description of Related Art
Japanese Patent Application Publication No. 2010-220387 (JP 2010-220387 A) describes a rotary electric machine in which a magnetic plate is inserted between coil wires that are stacked and wound in a concentrated winding around teeth of a stator. As a result, magnetic flux flows more easily to the magnetic plate, and is thus inhibited from flowing to the coil wires, which reduces an eddy current generated by a fluctuation in magnetic flux interlinked with the coil.
When magnetic flux that flows through the teeth of the stator becomes saturated when applying magnetic flux between the stator and the rotor, the magnetic flux leaks out from the teeth and flows out through the coil positioned between adjacent teeth (i.e., in the slot). The amount of leakage flux that flows through the coil between the teeth increases toward the tip end side of the teeth that is close to the rotor where the magnetic flux acts, and decreases toward the root (i.e., the base) side of the teeth that is farther away from the rotor. Also, when leakage flux that flows through the coil between the teeth fluctuates, an eddy current is generated in the coil, and loss resulting from this eddy current occurs. In particular, an eddy current due to fluctuation in the leakage flux that flows through the coil between the teeth tends to increase, and thus loss resulting from the eddy current also tends to increase, more in the coil positioned on the tip end side of the teeth that is close to the rotor.
The technology described in JP 2010-220387 A attempts to reduce an eddy current generated by a fluctuation in the magnetic flux that is interlinked with the coil, by facilitating the flow of leakage flux between the teeth to the magnetic plate inserted between the coil wires. However, the thickness of the magnetic plate inserted between the coil wires is constant from the tip end side of the teeth where the amount of leakage flux is large to the root side of the teeth where the amount of leakage flux is small. Therefore, the thickness (i.e., the width of the magnetic path) of the magnetic plate is excessive at the root side of the teeth. As a result, the conductor space factor between the teeth decreases.